Transcript Formulating Foods for Safety

Formulating Foods for
Microbiological Safety
Kathleen Glass, Ph.D.
Assistant Scientist
Food Research Institute
University of Wisconsin-Madison
President-Elect
International Association for Food Protection
BAFP 21 November 2003
Florianópolis Brasil
Formulation-safe foods
Definition of low acid (canned) foods
 Risks to consider
 Strategies to formulate safe foods

 Refrigerated foods
 Shelf-stable foods
 Convenience foods
 Meet changing needs of consumers “on the go”
Low acid foods

pH > 4.6 and aw >0.85
 Considered potentially hazardous if not refrigerated

United States: Low Acid Canned Foods
 Assumed to be shelf-stable
 Hermetically sealed container
 Often process-safe
 Inactivate microorganisms of public health significance
 “Retort” thermal processing; commercially sterile
 Primary concern: Clostridium botulinum
 Must file process with FDA
 Including all imported foods
Formulation-safe foods

Acid or acidified foods pH < 4.6
 Foods with water activity < 0.85
 Low acid foods with multiple
barriers
 Combination of pH, aw,
antimicrobials
 Recommend formulating certain
refrigerated foods for safety to
control psychrotrophic bacteria ex.
Listeria
Goal for formulating safe foods

General rule: < 1-log increase of pathogen for
time that is 1.5X shelf life as determined by
manufacturer
 Must be bacteriostatic

Processed meats
 No more than 1-log increase of LM during shelf-life

Other shelf-stable foods
 No botulinal toxin production 2x shelf-life

Need to consider whole food, individual
components, and interfaces of components
Risk analysis
 Pathogens
 Type and level of contamination likely in raw
ingredients and environment
 Infectious dose
 Growth vs. survival
 Thermal stability of pathogens
 Recontamination potential
 Presence
of competitive microflora
and expected shelf-life
Risk analysis

Storage temperature
 Shelf-stable vs. refrigerated
 “Traditional” vs. novel storage
Modified atmosphere packaging
 Temperature control during distribution
 Risk of temperature abuse at retail and
with consumers



Consider worse case scenario
Reevaluate if formulation changes
Do not rely on temperature
alone to protect foods



Pasteurization is not perfect
 Spore survive pasteurization
 Post-pasteurization contamination
Temperature abuse is common
 During distribution, at homes, poweroutages
Growth of psychrotrophic pathogens
 Listeria monocytogenes
 Nonproteolytic C. botulinum
 Some Bacillus cereus strains
Pathogens of concern:
“The Big-5”
Clostridium botulinum
 Listeria monocytogenes
 Staphylococcus aureus
 Enterohemorrhagic E. coli
 Salmonella

Other pathogens of concern

Clostridium perfringens
 Bacillus cereus
 Campylobacter
 Parasites and viruses

Control by:
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

Same formulation strategies as for “The Big-5”
Good manufacturing and good agricultural practices
Proper heating/cooling
Employee hygiene
Foods of concern



Foods that support growth of select
pathogens at refrigeration temperatures
Low acid foods with traditional storage at
room temperature
High risk foods that can be formulated for
enhanced safety





Refrigerated processed meats
Refrigerated foods / entreés with heat treatment
Process cheese products
MAP bakery products
Garlic-in-oil; herbs-in-oil (fresh; not pre-acidified)
Factors Affecting Growth
Acid and Water Activity

Gram-negative bacteria: acid tolerant
 Salmonella, Enterohemorrhagic E. coli survival pH <4.0
 Seldom grow at aw <0.95

Gram-positive bacteria: salt and aw tolerant
 S. aureus
Growth at aw 0.86
 Enterotoxin production ~ 0.91
 L. monocytogenes
 Growth at 0.92
 C. botulinum
 Growth at 0.93
 Minimal pH for growth 4.5 – 5.2 depending on acidulant

Useful Antimicrobials

Phosphate based emulsifiers
 C. botulinum in process cheese

Antimycotics (sorbate, benzoate, propionate)
 S. aureus, C. botulinum, L. monocytogenes

Organic acid salts (lactate, diacetate)
 C. botulinum, L. monocytogenes in meats/other foods

Nitrite (US usage 80-156 ppm)
 C. botulinum, L. monocytogenes in meats

Lysozyme (400 ppm in cheese)
 Clostridium sp.

Bacteriocins/nisin (250 ppm in cheese)
 Bactericidal against gram-positive bacteria
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Hurdle Technology
Temperature
Acidity
Water activity
Antimicrobials
Competitive
microflora
Proper fermentation
Nutrient availability
Oxygen content
Control of spores
Product treated to control vegetative cells and
protected from recontamination.
Critical aw
values
0.92 or less
Critical pH values
4.6 or less
>4.6– 5.6
>5.6
Non-TCS*
Non-TCS
Non-TCS
Temperature
Controlled for
Safety
>0.92–.95
Non-TCS
Non-TCS
?
>0.95
Non-TCS
?
?
Control of vegetative cells and spores
Product not treated or treated
but not protected from recontamination
Critical
aw values
Critical pH values
<4.2
4.2 – 4.6
>4.6– 5.0
> 5.0
< 0.88
Non-TCS
Non-TCS
Non-TCS
Non-TCS
0.88– 0.90
Non-TCS
Non-TCS
Non-TCS
?
>0.90–.92
Non-TCS
Non-TCS
?
?
>0.92
Non-TCS
?
?
?
USDA-ARS Pathogen Modeling Program 6.0
L. monocytogenes
7°C
40 ppm NO2
pH 5.9
Aw 0.99
7°C
40 ppm NO2
pH 5.3
Aw 0.975
Examples of
Formulation-Safe Foods
Formulating Processed Meats

Safety by good
manufacturing practices
and formulation
 Clostridium botulinum
Proteolytic vs.
nonproteolytic
 Listeria monocytogenes





Staphylococcus aureus
Clostridium perfringens
Enterohemorrhagic E. coli
Salmonella
Control Strategies for
Processed Meats
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Sodium lactate
Sodium diacetate
Sodium nitrite
Polyphosphates
Smoke
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


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Drying
Fermentation
Organic acids
Bacteriocins
Other
antimicrobials
Fermented dried sausage





Reduced pH and aw
Fermentation
 Organic acids – primarily lactic acid
 Bacteriocins
 Competition for nutrients
Nitrites
Effective against LM, C. bot, S.aureus
E. coli O157:H7 reduction usually requires
heat
E. coli and L. monocytogenes
AEM 58:2513
JFP 52:226
Refrigerated High-Moisture
Processed Meat Formulations
8
L. monocytogenes, 4°C
log cfu/g
7
6
Ham
5
Turkey
4
Wieners
3
Beef
2
Salami
1
0
0
2
4
6
Week
Glass and Doyle, AEM, 1989
Effect of
temperature and antimicrobials
L. monocytogenes on cooked sausage;
3.4% lactate / 0.1% diacetate
6
log cfu/g
5
4
unsmoked,3C
smoked,3C
unsmoked,7C
smoked,7C
3
2
1
0
0
2
Week 4
8
12
Glass et al, 2002, JFP 65:116
Effect of lactate and diacetate
Log cfu/pkg
LM, lactate/diacetate, wieners, 4C
11
1.32% L
10
2.0% L
9
2.5% L
8
3.0% L
7
3.5% L
6
1%L/.1% D
5
1%L/.25% D
4
2%L/.1% D
0
7
14
30
45
60
Day
Glass et al, 2002, JFP 65:116
Formulating Process Cheese
(Shelf-Stable)
pH 5.4-6.0
 Aw 0.94-0.96 cheese spread
 Aw 0.91-0.93 cheese slices

Controlling C. botulinum in
process cheese spreads
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Moisture
pH
Total salts
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NaCl
Phosphate-based
emulsifier
Water activity not
accurate predictor
of safety if 0.93-0.96
Applicable to
spreads with >51%
cheese; 20-25% fat
Tanaka et al, 1986
S. aureus, process cheese
10
Growth of S. aureus at pH >5.6; no sorbic acid
9
8
log CFU/g
7
6
5
4
3
2
1
0
0
0.5
1
1.5
2
3
4
7
days
Glass et al., Unpublished data, 2001
20 formulations – 2 lots each, 27C
Formulating Convenience Foods
Refrigerated cooked potatoes:
Control C. botulinum pH/aw/temp
°C
Day
4
7
14
30
45
60
103
pH 5.75, aw .995
4
12.8
27
--3/3
--3/3
0/3
0/3
Disc.
0/3
0/3
Disc.
0/3
1/3
Disc.
0/3
1/3
Disc.
0/3
Disc. Disc.
pH 5.8, aw .985
4
12.8
27
--0/3
--2/3
0/3
0/3
2/3
0/3
0/3
Disc.
0/3
0/3
Disc.
0/3
0/3
Disc.
0/3
Disc. Disc.
Chicken-broccoli-sauce entreé
Control C. botulinum by pH/lactate
Effect of sodium lactate and pH
Days to toxicity
#
pH
% H2 O
NaL
12.8°
27°C
1
2
3
4
5
6
6.3
6.4
5.5
5.1
5.1
4.8
80
80
84
80
80
82
-2.0
--2.0
--
7
7
35
35
>105
>105
7
7
7
7
>105
35
MAP Pizza Crusts
Control C. botulinum
aw/pH/sorbate
 supports toxin production
0.96
O no toxin production
0.95
Aw
0.94
0.93
0.92
0.91
0.9
5
5.2
5.4
Products contained 0.3% sorbic acid
5.6
pH
5.8
6
Fresh Pasta
Control C. botulinum aw/pH
production
0.98
º no toxin production
0.97
Filled
0.96
Aw
Check individual
components
* supports toxin
0.99
Unfilled
0.95
0.94
0.93
0.92
0.91
5.5
5.7
5.9
6.1
6.3
pH
6.5
6.7
6.9
What NOT to rely on for safety
Finished product testing for pathogens
 Proper handling and refrigeration
 Modified atmosphere packaging
 Pasteurization or irradiation alone

Rely on:
Secondary barriers
 GMPs and environmental controls
 HACCP

 Responsible for 70% decline in listeriosis
Good source of ingredients
 Proper and clear labeling

 Code dating
Use by…
How to start

Predictive modeling
 ARS Pathogen Modeling Program 6.0
 www.arserrc.gov/mfs/PATHOGEN.HTM
 Purac OptiForm Listeria Control Model
 FRI model for process cheese
Published results for specific foods
 Verify with challenge testing

Formulation Safety
Depends on Many Factors

Consider all sources of contamination
 Assume pathogens are present in raw
ingredients/environment
 Use high-quality raw materials with low
levels of microorganisms
 Reduce/prevent levels of contamination by
proper sanitation/heat treatment
Formulation Safety…continued

Multiple hurdles
 Synergistic interaction means that lower of
each factor can be used
 Consider effect of competitive microflora
 Assure that manufacturing specifications
are met
 Control storage temperatures wherever
possible

Educate consumer with clear code dates
and storage conditions on labels
For additional information:
Kathleen Glass, Ph.D.
Assistant Scientist
Food Research Institute
University of Wisconsin-Madison
1925 Willow Drive
Madison, Wisconsin 53593 USA
E-mail: [email protected]
Phone 608.263.6935; Fax: 608.263.1114
References

[NACMCF] National Advisory Committee
on Microbiological Criteria for Foods. 1998.
Hazard analysis and critical control point
principles and application guidelines. J
Food Prot 61:762-75.
 [NSF] NSF International. 2000 Nov. 10.
Non-potentially hazardous foods. Ann
Arbor (MI): NSF International. Report nr
ANSI/NSF 75-2000. 12 p.
 IFT Status Summary, Extended Shelf Life
Refrigerated Foods: Microbiological
Quality and Safety, Vol. 52. Feb. 1998.

IFT Task Force, December 31, 2001
 Evaluation and Definition of Potentially
Hazardous Foods
 Conference for Food Protection website
www.foodprotect.org